what is a safe out of balance voltage?

[Robb]

what I'm trying to figure out is how much "out of balance" can a lipo go without being trashed, I just had a 3s that read 4.17 4.17 3.69 (and didn't come back), I realise that .48v is a lot but what should I look for in the future that might be an indicator?

thanks
Robb

[HPSOV2]

Most batteries state that 4.23v is the maximum charging voltage. Above this voltage I believe you will start doing damage to the pack (however I believe that 4.3v is the 'danger' threshold).

The worst case while charging is that one cell is off the other two. 4.23 4.18 4.19. In this case you hit the 4.23v with a difference of 0.05v. I think this is a fair 'limit' at which to declare a pack out of balance. Remember this is at full charge, many packs will go out of balance during discharge, but will naturally return to balance when charged.

In the case of your pack this is more than a simple 'balance' issue, you have a dead cell which a balancer will not help.

FWIW I have packs with 40 cycles that have never been balanced, they were measured to be within 0.007v when the pack was purchased, and are still within 0.01v today.

[Pinecone]

From ThunderPower balancer instructions:

A: Imbalance under 0.03V: Yellow status LED “on” steady and red LED’s “on” for 5 seconds.
Normal charging, proceed as usual.
B: Imbalance 0.03 to 0.2V: Yellow status LED “off” and red LED’s flash for 5 seconds.
Charge at 0.3A to balance the pack or proceed carefully with up to 1A maximum charge rate.
C: Imbalance over 0.2V: Yellow status LED “off”and red LED’s flash for 60 seconds.
Battery may require repair. Keep battery plugged into the balancer until balancing stops.
DO NOT charge the battery until balancing stops.
If yellow status LED “flashes”, pack average voltage is below 3.6V.
Charge the pack to 3.7/Cell or above before checking packs condition
You must always avoid deep discharge to this level
Additional audio alert:
-If any of the individual cells in the battery fall below 3.2V, an audible beep will be emitted for 5
seconds.
-If the pack is charged to over 4.3V/cell (overcharged), audible beeps will be emitted continuously. The
pack will need to be discharged to below 4.2V/cell before continuing use of the balancer.